The goal of this one year pilot project is to pursue preliminary observations which suggest the existence of specific surface factors expressed by visual neurons undergoing naturally occurring cell death and the possibility that these factors regulate immune cell function. Monoclonal antibodies will be generated against superior colliculus membranes from rats bilaterally enucleated at birth to enhance cell death. Immunocytochemical screening against monocularly enucleated animals will reveal those antibodies that may react with membrane antigens present specifically on cells that are undergoing naturally occurring cell death. To study visual-immune system interactions, superior colliculus membranes from total enucleates will be used to quantify the regulatory effect of this material on macrophage proliferation and activation. Naturally occurring cell death in the visual system is a critical event in the generation of normal connectivity. Nervous-immune system interactions during development may regulate this event, but have not been studied in any detail. The data that we hope to obtain in this pilot study will be used to initiate a new direction in our research program - applying molecular probes and cellular immunology to the long-standing problem of cell death in the nervous system.